1. Field of the Invention
This invention relates to a rotary compressor and more particularly to the type of rotary compressor having a rotating piston.
2. Description of the Prior Art
Rotary pumps and compressors of the type having a rotating piston are well known in the art and generally comprise a housing defining a cylindrical chamber having an inlet and outlet and housing a cylindrical roller or piston of lesser diameter. The rolling piston is driven in rolling contact with the inside wall of the chamber and a retractable divider member extends outwardly from the chamber wall to sealingly engage the piston between the inlet and outlet opening and divide the chamber into an inlet or low pressure side and an exhaust or high pressure side. The rolling piston is driven about the inner wall of the chamber by an eccentric crank member on the axially disposed drive shaft of the compressor. For the most part, the eccentric crank is a solid member configured to force the rolling piston into compressive engagement with the chamber wall. However, in some instances, it is conceivable that a non-compressible material, such as liquid refrigerant, would enter the compressor chamber along with vapors to be compressed therein. This liquid material, being non-compressible, is quite apt to damage the compressor.
It is known in pumps having similar rolling piston configurations as the compressor of the instant invention to have a yieldable (e.g. spring) crank arm or linkage forcing the rolling piston into compressive engagement. This permits the non-compressible material in the pumped fluid to pass through the pump without damage thereto. U.S. Pat. No. 2,460,617 discloses a pump of this nature.
Further, it is recognized that the pumping capacity of a rotary pump can be regulated by adjusting the amount of eccentricity of the roller (e.g. from its full eccentric position in rolling contact against the inner wall of the pumping chamber providing maximum pumping capacity to a position of concentricity with the drive shaft wherein the pump would have no pumping capacity). However, such mechanical linkage involves a multiplicity of parts. U.S. Pat. No. 2,266,191 shows a mechanism in a rotary pump for adjusting the pump capacity.